For it is not death or pain that is to be feared, but the fear of pain or death.
οὐ γὰρ θάνατος ἢ πόνος φοβερόν, ἀλλὰ τὸ φοβεῖσθαι πόνον ἢ θάνατον.
Original text (Ancient Greek)
Variants
For death or pain is not formidable, but the fear of pain or death. (Book II, ch. 1)